The Galaxy S3 I9300 has been in the spotlight ever since its release and rising demand for the smartphone from Android community has further fuelled developer support, leading to a number of custom ROM Jelly Bean releases.

The SlimBean Build 3 ROM and the instructions given in this guide are meant for the international variant of the Galaxy S3 I9300 only. Verify device model number by navigating to Settings > About Phone

Back up data and settings via a recommended custom recovery tool, like ClockworkMod (CWM) or TWRP; it creates a complete image of the existing phone setup

Ensure device is unlocked (not locked to a specific carrier) and rooted with CWM Recovery

If device is stuck at booting or experiencing boot loop issues, perform Wipe Cache Partition and Wipe Dalvik Cache a few more times before rebooting

Allow newly installed ROM to stabilise for five minutes before you start working

Instructions provided in this guide are meant for reference purposes only. IBTimes UK will not be held liable if device is damaged or bricked during or after firmware installation. Users are advised to proceed at their own risk

Boot phone into ClockworkMod Recovery by pressing and holding Volume Up, Power and Home buttons until Samsung logo appears. Then release all three buttons and press again. The device will now enter CWM Recovery. Use Volume keys to navigate between option and Power to select an option in Recovery

Take a Nandroid backup of the existing ROM so it can be restored later if the new ROM fails to work or you want to return to the original ROM. To backup, choose Backup and Restore and then tap Backup on next screen. Return to main Recovery menu once task is complete